The invention relates to a process for the production of irregular non-woven material sheets which are drawn off in the form of a warp from spinnerets by means of a gaseous propellant generated by a compressor or the like and are deposited on a substrate. Furthermore, the invention relates to an apparatus for carrying out the process.
processes and apparatus of the above presupposed species are already known from German patent 1 785 158, British patent 1 282 176 and British patent 1 297 582. A common characteristic of these processes is that the warp is drawn off the spinnerets under the influence of compressed air by means of a filament draw-off device and, after passing through a spreading device, is deposited on the substrate in order to form an irregular non-woven material sheet.
An important aspect during the production of non-woven material sheets is the filament draw-off force occurring in the filament draw-off device which, in the known processes and apparatus, is mainly created inside a filament offlet having at its upper end a filament draw-off nozzle supplied with highly compressed air.
In practical use it has been shown that, although a sufficient filament draw-off force can be generated with the filament offlets, the filament offlets have, however, a disadvantage in another way. It is possible that within the narrow filament offlets--the inner diameter is, for example--around 3 mm--the individual filaments can become tangled, which has the troublesome result that the structure of the irregular non-woven material sheets is not uniform. However a definite characteristic of the quality of an irregular non-woven material sheet is as uniform a structure as possible.
This is where the invention comes into play, by means of which a process and an apparatus is to be created which permit the production of irregular non-woven material sheets with as uniform a structure as possible.